Petrography and geochemistry of intrusive rocks in the Shurchah antimony-bearing area, Southeast of Zahedan


1 گروه زمین شناسی، دانشکده علوم، دانشگاه سیستان و بلوچستان، زاهدان

2 گروه زمین شناسی، دانشکده علوم، دانشگاه سیستان و بلوچستان، زاهدان، ایران Department of Geology, Faculty of Sciences, University of Sisatna and Baluchestan, Zahedan, Iran


The Shurchah antimony-bearing area is located in the Eastern Iranian flysch zone.The Cretaceous to Eocene schists and phyllites are the oldest geological units in the area. These rocks have been intruded by granitic bodies, felsic dikes, and quartz and stibnite veins. The granitic rocks in this area are composed of granite, granodiorite and aplite dikes. The granitoid rocks are generally massive, gray and coarse-grained with granular, porphyritic and cataclastic textures and contain mainly plagioclase, K-feldspar, quartz, biotite, muscovite and opaques. These rocks are commonly peraluminous to metaluminous, calc-alkaline and related to a magmatic arc. The SiO2 content of the intrusions varies from 61 to 75 wt.%. Variation diagrams show linear trends, with increasing SiO2 content Al2O3, CaO, FeOt, MgO, and TiO2 amounts decrease whereas, K2O and Na2O contents increase. On the base of MORB and ORG- normalized diagrams, the negative anomalies of Nb, Ti and positive anomalies of K, Rb, Th, U and especially Pb revealed an igneous mantle origin, especially the role of Sistan subduction oceanic crust and overlaying mantle wedge in the genesis of these rocks and also, the role of continental crust in magmatic contamination.